The present invention relates to an image forming apparatus capable of developing a copy image on a copy paper sheet, in a single cycle of its copying operation, using a developing agent of any desired color, and more specifically relates to an image-forming apparatus, such as a color copying machine, in which developing agents of different colors are used individually, in a plurality of cycles of its copying operation, repeated for a single sheet of copy paper, thereby permitting multicolor copying.
Development of color versions has recently been promoted in the field of copying machines. For example, two-color copying machines have been developed for practical use, which can produce color images enjoying another color as well as black. In the conventional color copying machines of this type, however, developing agents of different colors are used individually in a plurality of cartridges which each include a developing unit and a photosensitive member in integral relation. A plurality of color copying operations are performed by alternatively replacing the cartridges with one another. Thus, the prior art color copying machines require a troublesome series of operations.